Upper-Oceanic Warming in the Gulf of Mexico between 1950 and 2020

Abstract

We estimate ocean heat content (OHC) change in the upper 2000 m in the Gulf of Mexico (GOM) from 1950 to 2020 to improve understanding of regional warming. Our estimates are based on 192 890 temperature profiles from the World Ocean Database. Warming occurs at all depths and in most regions except for a small region at northeastern GOM between 200 and 600 m. GOM OHC in the upper 2000 m increases at a rate of 0.38 6 0.13 ZJ decade21 between 1970 and 2020, which is equivalent to 1.21 6 0.41 terawatts (TW). The GOM sea surface temperature (SST) increased;1.08 6 0.258C between 1970 and 2020, equivalent to a warming rate of 0.198 6 0.058C decade21. Although SST in the GOM increases at a rate approximately twice that for the global ocean, the full-depth ocean heat storage rate in the GOM (0.86 6 0.26 W m22) applied to the entire GOM surface is comparable to that for the global ocean (0.82–1.11 W m22). The upper-1000-m layer accounts for approximately 80%–90% of the total warming and variations in the upper 2000 m in the GOM. The Loop Current advective net heat flux is estimated to be 40.7 6 6.3 TW through the GOM. A heat budget analysis shows the difference between the advective heat flux and the ocean heat storage rate (1.76 6 1.36 TW, 1992–2017) can be roughly balanced with the annual net surface heat flux from ECCO (237.9 TW).